◆ Resin

Alphabet resin keychain mold, J to R

Nine bubble letter keychains, J to R, each with a key ring hole. The middle tray of a full resin alphabet.

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3D render of the printed caster for an alphabet resin keychain mold with the letters J to R, and nine light blue bubble letter keychains with ring tabs in front
Resin ~83 g Pro early access

A silicone mold for nine chunky letter keychains, J, K, L, M, N, O, P, Q and R, in a rounded bubble typeface 35 mm tall and 5.5 mm thick. A round tab on each letter carries a post in the cavity, so each keychain comes out with a 3.8 mm hole for the jump ring, with the counters of O, P, Q and R open and no drilling.

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Made with our tray mold generator in its flexible silicone tray mode: print one part, a caster, pour a platinum silicone into it and peel it out. That silicone is the resin mold: it releases epoxy or UV resin with a gloss and no release agent, and it flexes off the thin tails of J and Q without snapping them. The set of nine takes about 48 ml of resin.

This is the middle tray of three (A to I and S to Z and & are separate designs, and there is a 0 to 9 number tray). The zip carries the printed caster exactly as the tool exported it, the nine letters on their own as an STL, the master uploaded to the tool, and a print and pour sheet with the silicone figure the tool measured.

Shown as a 3D render of the printed caster with the nine light blue resin letters in front, not a photo.

Alphabet resin keychain mold, J to R at a glance: every printed part with its size, print time, filament, print settings and the three steps to use it

What you need

4
  • About 246 ml of platinum silicone (mix it in one batch)
  • About 48 ml of epoxy casting resin for all nine letters, or UV resin
  • Pigment paste, mica or glitter, and a few toothpicks for the small corners
  • Jump rings (6 to 8 mm), key rings, nitrile gloves and a heat gun or lighter

How to cast it

5

  1. Print the caster as exported, open side up, no supports. Turn on ironing for the top surfaces, or sand the raised shapes smooth and brush on XTC-3D: the silicone copies every layer line, and resin shows each one on its glossy face.

  2. Mix 246 ml of platinum silicone and pour it into one corner of the caster in a thin stream until it covers the shapes to the rim. Tap out the bubbles, let it cure as long as its datasheet says and peel it out. That silicone is your resin mold: platinum silicone gives resin a glossy face and needs no release agent.

  3. Work in a ventilated room with nitrile gloves on. Mix epoxy casting resin exactly at the ratio on the bottle, stir slowly for three minutes scraping the sides, and let it rest a few minutes so the bubbles rise.

  4. Glitter, mica or dried flowers go in face down: the side against the silicone is the front. Fill each cavity to just below the top of its post (all nine letters take about 48 ml together) so the hole stays open, and pass a heat gun or a lighter quickly over the surface to pop the bubbles. Cover the mold against dust.

  5. Leave epoxy 24 hours (UV resin: cure each layer under the lamp), then flex the mold and peel it off the pieces rather than pushing them out. Let epoxy harden two more days before you fit jump rings, hooks or a tassel.

Print details

2 h 50 minPrint time
~83 gFilament
1Printed parts
135 × 166 × 18 mmSize (W x D x H)
All print details
Print details
Cast materialResin
Printed parts1
Size (W x D x H)135 x 166 x 18 mm
Print bed needed166 x 135 mm, 18 mm tall
Filament~83 g
Layer height0.2 mm
Infill15%
SupportsNot needed
DownloadZIP: printed caster (STL) + one set of nine letters (STL) + tool master (STL) + print and pour sheet
Added2026-09-27

Pro early access until October 27, 2026, then free with any account.

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Make your own tray mold →

Made with the free Tray mold generator. Upload your own model and get the same kind of mold built around it, in your browser.

Free for personal use. Selling the pieces you cast needs a commercial licence (Pro or Founder); passing on the file itself is not permitted on any plan. Full terms.

New to casting? Read the ice cube tray mold guide.

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Questions about this design

How do I stop bubbles in the corners of the J to R letter keychains?

Drip a little resin into each cavity first and push it into the corners of M, N and K with a toothpick, then fill the rest. Pour thin, from a few centimetres up, and pass a heat gun over the tray after a few minutes. A warm room (22 to 25 C) lets the bubbles rise before the resin thickens.

Will the tail of the Q or the J break when I demold the letter keychains?

Not if the resin is fully hard. Leave epoxy at least 24 hours, then peel the silicone back from the letter instead of pushing the letter out, starting at the widest part and leaving the tail for last. A soft, bendy letter needs another day before it comes out.

Can I add a glitter edge to the letters from the J to R resin mold?

Yes. Brush a little chunky glitter along the walls of each cavity before you pour, or pour a thin clear layer, sprinkle glitter at the edge and fill once it gels. The side against the silicone is the front of the keychain, so what you put down first shows most.

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